1. Technical Field
This invention relates to a pheromone, and more particularly, to the new aggregation pheromone for the bark beetle Ips pini, lanierone (4,4,6-trimethyl-2-hydroxy-2,5-cyclohexadiene-1-one).
2. Description of the Prior Art
Throughout this application various publications are referenced by arabic numerals within parentheses. Full citations for these references may be found at the end of the specification immediately preceding the claims. The disclosures of these publications in their entireties are hereby incorporated by reference in this application in order to more full describe the state of the art to which the invention pertains.
The pine engraver, Ips pini Say, breeds in pines and spruces throughout most of North America. Upon locating a host tree, males bore into the phloemcambium region and release a chemical attractant (pheromone). Ips pini kills pines and spruces throughout North America, therefore, a means of controlling this pest is highly desirable.
The mass attacks on host trees by these insects is known to be guided, at least in part, by the pheromones emitted by the insects. These pheromones act as aggregating agents to attract other beetles of the species to a food supply and to mating opportunities. Exploitation of the insects reliance on an aggregation pheromone to bring the sexes together offers intriguing possibilities for insect control.
A number of economically important insects are currently monitored, partially controlled, or completely controlled by use of their own specific pheromone. The use of pheromones has also been reported for locating, surveying, or monitoring pest populations at levels not otherwise detectable. The following U.S. Patents, for example, disclose insect pheromones and their uses: U.S. Pat. No. 4,034,080, issued Jul. 5, 1977 to Silverstein et al. (European Bark Beetle); U.S. Pat. No. 4,179,446, issued Dec. 18, 1979 to Tumlinson, III et al. (Japanese Beetle); U.S. Pat. No. 4,291,051, issued Sep. 22, 1981 and U.S. Pat. No. 4,357,339, issued Nov. 2, 1982, both to Wilson et al. (Pine Beetles); U.S. Pat. No. 4,990,331, issued Feb. 5, 1991 to Slessor et al. (Honey Bees); U.S. Pat. No. 4,992,268, issued Feb. 12, 1991 to Landolt et al. (Papaya Fruit Fly); U.S. Pat. No. 4,474,991, issued Oct. 2, 1984 and U.S. Pat. No. 4,565,695, issued Jan. 21, 1986, both to Guss et al. (Southern Corn Rootworm); and U.S. Pat. No. 4,871,537, issued Oct. 3, 1989 to Chuman et al. (Banded Cucumber Beetle).
In the case of Ips pini, the aggregation pheromone was reported to consist of a single compound, ipsdienol (1,10). More recently, Greis et al. (7) reported that I. pini in British Columbia produce E-myrcenol and Miller et al. (14) reported that E-myrcenol was behaviorally active for I. pini in British Columbia. In addition, .beta.-phellandrene, a major constituent of the terpene fraction of lodgepole pine oleoresin (Pinus contorta var. latifolia Engelmann) is attractive to I. pini in British Columbia (13).
Interpopulational pheromonal specificity (8) has been reported to be based on ipsdienol enantiomeric composition (1,10). In general, western populations produce and respond to blends of over 90% (-)-ipsdienol [less than 10% (+)] and eastern populations produce and respond to a nearly racemic mixture of ipsdienol [roughly 50:50 (-):(+)]. The specificity of response to pheromones can also vary seasonally within a population. A New York population of I. pini responded in the spring and early summer to natural pheromone sources but not to racemic ipsdienol, while in the later summer and fall the number of beetles trapped by ipsdienol and natural sources were not significantly different. In addition, laboratory reared beetles originating in New York are attracted to a pheromone extract, but not to ipsdienol in laboratory bioassays. This demonstrates that one or more additional compounds are required for response.
The identification of the additional component(s) of the bark beetle pheromone is necessary in order to use the pheromone to control these insect pests. To this end, applicants have isolated and identified a new pheromone component for I. pini through the use of the fractionation and bioassay method of Silverstein et al. (16). The new component is a new natural product and is designated "lanierone," in recognition of the late Gerald N. Lanier and his valuable contributions to bark beetle chemical ecology.